Get Cosmopolitan into releasable state

A new rollup tool now exists for flattening out the headers in a way
that works better for our purposes than cpp. A lot of the API clutter
has been removed. APIs that aren't a sure thing in terms of general
recommendation are now marked internal.

There's now a smoke test for the amalgamation archive and gigantic
header file. So we can now guarantee you can use this project on the
easiest difficulty setting without the gigantic repository.

A website is being created, which is currently a work in progress:
https://justine.storage.googleapis.com/cosmopolitan/index.html

libc/calls/sigemptyset.c

@@ -18,13 +18,15 @@
 │ 02110-1301 USA                                                               │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/calls/sigbits.h"
-#include "libc/calls/calls.h"
+#include "libc/str/str.h"
 
 /**
  * Removes all signals from set.
  *
  * @return 0 on success, or -1 w/ errno
- * @error EINVAL
  * @asyncsignalsafe
  */
-int(sigemptyset)(sigset_t *set) { return sigemptyset(set); }
+int sigemptyset(sigset_t *set) {
+  memset(set->__bits, 0, sizeof(set->__bits));
+  return 0;
+}